The Walk method issue

[jzakrzewski]

I tried to Walk all the nodes of a Document starting from root, print all node names, and attributes for the Element nodes. There's however a problem:

root.Walk(func(n types.Node) error {
        fmt.Fprintln(os.Stdout, n.NodeName())
        if n.NodeType() == dom.ElementNode { 
            e := n.(types.Element)
            attrs, err := e.Attributes()
            if err != nil {
                return err
            }
            for _, a := range attrs {
                fmt.Fprintln(os.Stdout, "\t"+a.NodeName())
            }
        }
        return nil
    })

panics at runtime with panic: interface conversion: *dom.XMLNode is not types.Element: missing method AppendText. I've also tried e := n.(*dom.Element) only to get panic: interface conversion: types.Node is *dom.XMLNode, not *dom.Element.

I've debugged a bit and it seems that the receiver gets converted to *dom.XMLNode because of the Walk method receiver type. I can work this around by calling doc.Walk... but it won't work if I wanted to start from an arbitrary node.

Sorry I won't fix it myself but I've just started with go and I don't feel like I could do it right.

[lestrrat]

@jzakrzewski I know this is old, but if you still got code that reproduces this, that would be great. It sure sounds like an omission on my part.

[malamud]

Hi @jzakrzewski @lestrrat Maybe it will help to solve this issue or to fix it. I've got the same problem when I tried to walk over nodes panic: interface conversion: *dom.Text not types.Element: missing method AppendText But I've noticed that in test the same method worked. The difference is a content of xml files Walking through this one works fine:

<?xml version="1.0" encoding="UTF-8"?><Data xmlns="http://www.example.com/OTA/2003/05"><Dates start='1987-01-12'/></Data>

This xml causes panic:

<?xml version="1.0" encoding="UTF-8"?>
<Data xmlns="http://www.example.com/OTA/2003/05">
    <Dates start='1987-01-12'/>
</Data>

This helped me XMLParseNoBlanks

d, err := libxml2.ParseString(s, parser.XMLParseNoBlanks)

Or replace new lines and spaces between nodes but it is not an elegant solution.

[jzakrzewski]

@lestrrat damn! I've missed your comment somehow... I'm not sure if I have it. I guess I have implemented something else instead. But yeah, I can check what was it all about.

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